Semiconductor device such as diodes, transistors, or thyristors, to name only some, include doped semiconductor regions in a semiconductor body. Some types of these semiconductor regions such as, for example, emitter regions in a diode, source and drain regions in a transistor device, or collector and emitter regions in a thyristor are connected to contact layers that make it possible for the device to be interconnected with other devices, a printed circuit board, or the like. Those contact layers are ohmically connected to the respective semiconductor regions. “Ohmically connected” means that there is no rectifying junction between the contact layer and the respective semiconductor region.
Forming a metal layer on a semiconductor body may include depositing a metal layer on a surface of the semiconductor body, and heating the metal layer and the semiconductor body to a temperature of about 980° C. or higher. Such high temperatures, however, may not be compatible with processes in the manufacturing process. There is therefore a need to form a contact layer that is in ohmic contact with the semiconductor body at lower temperatures.